Electromagnetic translating device



April 24, 1956 R. G. THOMPSON 2,743,398

ELECTROMAGNETI C TRANSLATING DEVICE RUS SELL G'. THOMPSON nventor ATTORNEY E AGENT April 24, 1956 R. G. THOMPSON 2,743,398

ELECTROMAGNETIC TRANSLATING DEVICE Original Filed July 18, 1950 2 Sheets-Sheet 2 RUSSELL G. THOMPSON Snvntor ATTORNEYLQAGET United States Patent 2,143,398 ELECTROMAGNETIC TRANSLATING DEVICE Russell G. Thompson, Rochester, N. Y., assignor to East man Kodak Company, Rochester, N. Y., a corporation of New Jersey Original application July 18, 1950, Serial No. 174,423, n ow Patent No. 2,659,652, dated November 17, 1953. Divided and this application December 18, '1952, Serial No. 326,758

The present invention relates to signaling and more particularly to the high speed recording of facsimile or coded messages upon a record surface and is' a division of my copending application Serial No. 174,423 tiled July 18, 1950, now U. S. Patent No. 2,659,652.

'Ihe primary object of the invention is to provide an apparatus for producing visible characters from a plurality of character-forming signals received successively in groups.

Another object of the invention is to provide multiplex facsimile apparatus wherein a pluralityof printing styli are arranged close together in a row for parallel scanning and are independently and simultaneously vibrated in accordance with received signals by individual electromagnetic drivers.

Another object of the invention is to provide a multiple styli printer actuated by a translating device' comprising a plurality of vibrators polarized by the llux ina single magnetic circuit.

Another object of the invention is td provide any elec, tromagnetic translating device having two alined airgaps and having an armature extending into one of the airgaps and a core centered in the other airgap whereby the armature is pivoted outside the device.

Other objects of the invention including the provision of a compact, eiiicient, high-speed multiple styli recording device will become apparent from the following description of apparatus embodying the invention when read in connection mth the aceompanying'drawings in which: t

Fig. l is a view in perspective of a recorder constructed in accordance with the invention;

Fig'. 2 is a top plan view with a part broken away' of the electromagnetic driver of Fig.Y l;

Fig. 3 is a section along the line F3 in Fig. 2;

Fig. 4 is a partial view partly in sectionfof arepresentative portion of the vibrator units of the electromagnetic driver of Figs. 1-3;

Figs. 5 and 6 are partial side and top views', respectively, of printing arms having their styli ends interleaved to increase definition while using sturdy printing arns.

The recorder according tothe preferred form of the` invention comprises a plurality of styli arranged in a row and adapted to be actuated by individual electromagnetic drivers sharing a common magnetic circuit and so mounted that the motion from each driver to its associated stylus is transmitted in a single plane and without twist.

The signals for actuating the drivers may be obtained by scanning characters or may be produced synthetically by any suitable means to provide properly timed pulses in predetermined combinations so that as a recording medium is fed transversely' past the row of styliV it will be marked to build up the character corresponding tothe received signals.

For recordingv a single line of characters it has been found that seven-line definitionl produces very satisfactory results and for the purpose of illustrating the invention eight styli arranged in a row for parallel scanning are yof magnetic material.

2,743,398 Patented Apr. 24, 1956 vshown in Fig. 1, although the invention is not restricted to any specific number of recording elements. One reason eight styli are chosen for recording seven-line definitti-0n is to compensate for possible unevenness of a line of characters being scanned at a transmitter from which the recorder receives its signals. That is, although the characters being scanned are the height of seven pickup scanning elements, eight such scanning elements are em ployed so that a slight lateral shift in the characters being scanned can be tolerated. AIf the received signals are derived from code wheels or the like then only seven styli need be employed.

The recorder shown in Fig. 1 comprises eight printing bars 10 provided with printing pointsv or styli 11 arranged in a row. Each of the printing barsA 10 isnan arm of a bell crank lever, the other arm 12 of which is provided with an armature 13 and all of the levers are pivotally mounted on a suitable rod 14 for oscillatory movement about a common axis. The bell crank levers are made from thin flat stock and are assembled in adjacent parallel planes so that movement of the armatures 13 in these planes is transmitted without twist to the recording points 11.

In an operating embodiment the bell crank levers comprised of the printing arms 10 and the operating arms 12 are .02 inches thick and in order to accommodate individual vibrators for the several armatures 13 the angles made by the' arms 10 and 12 differ progressively by a given amount so that with the printing arms 10 in a plane normal to the plane of the bell crank levers the operating arms 12 are fanned out about the pivot rod 14. Electro 'magnetic vibrator pole pieces 15 mounted on a main frame 16 of nonmagnetic material with their airgaps radially alined with the' respective operating arms 12 share a common magnetic flux which may be provided by a permanent magnet 17 and its associated yokes 18 The vibrator pole pieces 15 are laminated and preferably made from high frequency electric sheet steel. Also, the pole members 15 are preferably mounted on different levels to correspond to the levels of the operating arms 12 and this may conveniently be done by machining steps 19 (see Fig. 2) of the proper height-on the main frame 16. A core or stationary armaturev 20' is centered by nonmagnetic fittings 21 and 22 in one of the airgaps of each vibrator and extends towards the other airgap in which the armature tip 13 of the operating arm 12 is suitably centered as by leaf springs 23 of nonmagnetic material which may' be secured to the exposed ends of the laminated poles 15. The armatures 13, which are of course magnetic, are secured to the ends 0f the nonmag'netie operating arms 12 in any suitable manner as by brazing or welding. The adjacent ends of the cores 20 and the movable armatures 13 should form as narrow an airgap' as possible'.

Each stationary armature or core 20 is surrounded by coils C comprising two oppositely wound activating coils 50 and 51 which are energized, respectively, through suitable leadsV 24 and 25, and 24 and 26 (see Figs. 3 and 4) to move the armature 13 in either of two directions to raise or lower the printing arms 10. The coils C can bevarranged in any manner as long as the ampere turns in each coil are equal, e.v g., the two coils can be arranged adjacent each other along armature 20 or in the preferred embodiment can be superimposed over each other as is well-known in the art. With this arrangement, one of the coils carries current on white, no current on black; and the other coil carries current only on black. The ux pp supplied by the permanent magnet 17 passes throughy the yokes 18 and serially throughv the pole pieces 15 and, since the airgaps are the same' between the poles 15 and the cores 20 and the poles 15 and the armatures 13, the ux gbp divides equally be- 3 tween the two pairs of pole faces of each vibrator. When there is no current in either of the coils 50 or 51 practically no ilux passes radially through the pole pieces 15 or the cores 20.

Current in either of the coils 50 or 51 in any vibrator produces a ux pc in the core 20 and the armature 13 and 1/mpc in each adjacent pole piece 1S comprising such vibrator. With this arrangement it is well understood that the armature 13 will be moved to raise or lower its associated printer bar 10 depending upon the direction of the flux qbc which, of course, depends upon which of the coils C is actually activated. Thus, the application of suitable signal currents to one of the coils C will create an unbalance which will pull the armature 13 to one side and when the other coil is activated, the armature 13 will be moved in the other direction. Since one coil carries current only on white and the other only on black when in operation, the printer bars 10 and their styli 11 are normally maintained in a raised position by one coil until the application of a suitable signal to the other coil changes the flux direction which causes the armature 13 to move to the other side. Upon completion of the signal to the other coil, the rst-mentioned coil is immediately activated to again raise the bars and styli. Hence, the coils C selectively raise or lower the printer bars 10 and their styli 11 to record the characters represented by the signal currents on a suitable recording medium, such as'a paper tape 27 and an overlying strip of carbon paper 28, which is moved transverselyV to and between the row of styli 11 and a solid surface (shown in Fig. 1 as comprising a drum 29) in any suitable manner as by rollers 30 actuated by mechanism, not shown, to advance the recording medium in the desired time relation with the received signals. This relation is not critical because for a given signal rate any variation in the speed of movement of the recording medium above or below an assumed ideal speed will merely result in a lengthening or foreshortening of the character in the direction of movement.

Referring now to Figs. 3and 4, rebound of the printer arms 10 is prevented by dampening which may conveniently be accomplished by meansV of felt pads 31 pressed against opposite sides of each operating arm. 12 by stud screws 32 in threaded engagement, respectively, with the main frame 16 and an arcuate yoke 33 spaced from and secured to the'main frame 16 by blocks 34. The pressure on the pads 31 is adjustable by turning lthe screws 32 which may be held in adjusted'position .by suitable lock nuts 35. Y

rThe nonmagnetic fittings 21 and 22 for clamping the cores 20 are shown in more detail in Fig. 4. The fitting 21 is integral with or rigidly secured to the main frame 16 with its radial faceV accurately located for positioning one side of the core 20, the other side of which is engaged by the'radial face of the fitting 22. The contacting surfaces of the ttings 21 and 22 are inclined with respect to their radial faces so that a screw 36 passing freely through the piece 21 and threaded inV the piece 22 will when tightened force the radial face of the piece 22 firmly against the core 20.

A modified arrangement shown in Figs. and 6 makes it Ypossible to record greater definition while retaining the desired sturdiness. YAs here shown, two recording units 37 and 38, similar to the one described above, are

Varranged on opposite sides of the recording line with their styli 3g interleaved. Preferably the interleaved portions of the printing arms 40 on which the styli are formed are reduced in thickness to permit a greater number of printing elements per'inch and still allow Vthe use of sturdy printing arms 40. Also, as shown in Fig. 5, the recorder according to the invention may be used to print on thick at stock such as tabulating cards by advancing a card 41 and a carbon paper 42'over a platen such as printing roller 43 and beneath the styli 39 at the desired rate by any suitable means such as two pairs of feed rollers 44.

It is preferred to use ilat sheet stock for forming the bell cranks and to assemble the bell cranks in sliding engagement with one another so as to provide a certain amount of mutual lateral support. However, if desired, thin spacers may be inserted between the several bell cranks.

It will be noted that the several bell cranks are identical, except for the angle between their arms, so as to have the same weight and the same moment of inertia.

.This makes possible uniform print results .since the application of equal lforces to the several armatures 13 will produce equal acceleration in the printing arms 10 and thus the impact of each printing element or styli 11 on the carbon paper is the same, the slight differences due to gravity being ignored. It is important to uniform printing that the radius of gyration around the common axis be the same for each bell crank. Y

It is to be understood that the term bell crank is used in a broad sense to include a rocker, i. e., the two arms make an angle greaterk than degrees, and that several recording units may be arranged in groups, one unit for each line or column to be recorded, so that several lines of characters may be recorded simultaneously.

While for the purpose of describing the invention a specific embodiment has been disclosed in detail, it will be obvious to those skilled in the art that various modifications will suggest themselves without departing from the scope of the invention as pointed out in the appended claims.

. Having now described my invention, what I desire to secure by Letters Patent of the United States and what I claim is: v Y

1.. An electromagnetic translating device comprising means for producing a steady magnetic ilux, pole members spaced to provide two airgaps in spaced and aligned relation for dividing the magnetic flux, a stationary core of magnetizable material extending through one of said airgaps and toward the other of said airgaps, an armature having a free end and pivotally mounted remote from said free end, said free end being disposed in said other of the airgaps and in-close proximity to said stationary core, and an activating means including two oppositely wound coils disposed between said pole members and said airgaps and surrounding said stationary core for moving said armature toward one side of the other of said airgaps in accordance with the coil activated.

2. An electromagnetic translating device comprising permanent magnetic means for producing a steady magnetic ux, a plurality of pole members arranged with respect to said magnetic means to provide a plurality of two airgaps in spaced and aligned relation for dividing the magnetic tiux, stationary cores of magnetizable material extending through each of one of said airgaps and toward the other of said airgaps, a plurality of armatures having free ends and pivotally mounted remote from said free ends, each of said free ends being disposed respectively in the other of said airgaps and in close proximity to` said stationary cores, and an activating means including two oppositely wound coils disposed between each of said pole members and each of said airgaps and surrounding said stationary corertherebetween for moving said armatures toward one side of the other of said airgaps in accordance with the coils activated.

3. An electromagnetic translating device comprising permanent magnetic means for producing a steady magnetic flux, a plurality of pole members arranged with respect to said magnetic means to provide a plurality of two aligned airgaps for dividing the magnetic ux, each of saidtwo airgaps being radially aligned and spaced with respect to a common center, a stationary core of magnetizable material extending radially through each of one of said airgaps and toward the other of said airgaps, a plurality of armatures having free ends and pivotally mounted at said common center remote from said free ends, each of said free ends being disposed respectively in the other of said airgaps and in close proximity to said stationary cores, and two oppositely wound energizing coils disposed between each of said pole members and each of said two airgaps and surrounding said stationary core therebetween for moving said armatures toward one side of the other of said airgaps in accordance with the coils activated.

4. An electromagnetic translating device comprising a non-magnetic supporting member, permanent magnetic means carried by said supporting member for producing a steady magnetic flux, a plurality of pole members spaced from said magnetic means and arranged on said supporting member about a common center to provide a plurality of two aligned airgaps for dividing the magnetic flux, said airgaps being radially aligned and spaced with respect to said common center, yoke members of magnetizable material connected to said magnetic means for conveying the magnetic ux serially through said pole members, stationary cores of magnetizable material mounted on said supporting member and extending radially through each of one of said airgaps and toward the other of said airgaps, a plurality of armatures pivotally mounted on said supporting member at said common center and having the free ends thereof disposed respectively in each of said other of the airgaps and in close proximity to said stationary cores, and an activating means including two oppositely wound coils disposed between each of said pole members and each of said two aligned airgaps and surrounding said stationary core for moving said armatures in either of two directions toward one side of the other of said airgaps in accordance with the coils activated.

5, An electromagnetic translating device comprising a non-magnetic supporting member, a bar magnet carried by said supporting member for producing a steady magnetic iux, said bar magnet having one surface thereof generated about a center of curvature, a plurality of pole members spaced from said one surface and arranged on said supporting member to provide a plurality of two aligned airgaps for dividing the magnetic ux, said airgaps being radially aligned and spaced with respect to the center of curvature of said bar magnet, yoke members of magnetizable material connected to said bar magnet for conveying the magnetic flux serially through said pole members, stationary cores of magnetizable material mounted on said supporting member and extending radially with respect to the center of curvature of said bar magnet through each of one of said airgaps and toward the other of said gaps, a plurality of armatures pivotally mounted on said supporting member at the center of curvature of said bar magnet and having the free ends thereof disposed respectively in each of said other of the airgaps and in close proximity to said stationary cores, and an activating means including two oppositely wound coils disposed between each of said pole members and each of said two aligned airgaps and surrounding said stationary cores for moving said armatures in either of two directions toward one side of the other of said airgaps in accordance with the coils activated.

References Cited in the le of this patent UNITED STATES PATENTS 268,237 Johnson Nov. 28, 1882 2,056,745 Stalnaker Oct. 6, 1936 2,277,308 Dillard Mar. 24, 1942 2,580,123 Peger Dec. 25, 1951 2,691,749 Durkee Oct. 12, 1954 

